Negative electrode for all-solid-state secondary battery, and all-solid-state secondary battery

Abstract

A negative electrode for an all-solid-state secondary battery according to the present invention includes a molded body made of a negative-electrode mixture containing a solid electrolyte and a negative-electrode material that contains a negative-electrode active material. The negative-electrode material contains a carbon material as the negative-electrode active material, and an argyrodite-type sulfide-based solid electrolyte is contained as the solid electrolyte. An AB value is 0.1 or more and 0.8 or less where a percentage of the area of the carbon material to the area of a surface of the molded body is A(%) and a percentage of the area of the carbon material to the area of a cross-section of the molded body is B(%). Also, an all-solid-state secondary battery according to the present invention includes the negative electrode for an all-solid-state secondary battery according to the present invention as the negative electrode.

1 . A negative electrode for an all-solid-state secondary battery, the negative electrode comprising:
 a molded body made of a negative-electrode mixture containing a solid electrolyte and a negative-electrode material that contains a negative-electrode active material,   wherein the negative-electrode material contains a carbon material as the negative-electrode active material, and   an argyrodite-type sulfide-based solid electrolyte is contained as the solid electrolyte, and   an A/B value is 0.1 or more and 0.8 or less where a percentage of the area of the carbon material to the area of a surface of the molded body is A(%) and a percentage of the area of the carbon material to the area of a cross-section of the molded body is B(%).   
     
     
         2 . The negative electrode for an all-solid-state secondary battery according to  claim 1 ,
 wherein the A/B value is 0.1 or more and 0.6 or less.   
     
     
         3 . The negative electrode for an all-solid-state secondary battery according to  claim 1 , comprising
 only hard carbon as the negative-electrode active material,   wherein the A/B value is 0.2 or more and 0.6 or less.   
     
     
         4 . The negative electrode for an all-solid-state secondary battery according to  claim 1 , comprising
 only graphite as the negative-electrode active material,   wherein the A/B value is 0.1 or more and 0.4 or less.   
     
     
         5 . The negative electrode for an all-solid-state secondary battery according to  claim 1 ,
 wherein a layer containing a solid electrolyte is formed on a surface of the negative-electrode material.   
     
     
         6 . The negative electrode for an all-solid-state secondary battery according to  claim 1 ,
 wherein the content of a binder in the molded body made of the negative-electrode mixture is 0.5 mass % or less.   
     
     
         7 . An all-solid-state secondary battery comprising:
 a positive electrode;   a negative electrode; and   a solid electrolyte layer located between the positive electrode and the negative electrode,   wherein the all-solid-state secondary battery includes the negative electrode for an all-solid-state secondary battery according to  claim 1  as the negative electrode.